Polyether ketone ketone (PEKK) polymers have a number of properties which make them useful in applications involving exposure to high temperature or to high mechanical or chemical stress. They are, for instance, useful in the aerospace industry, in off-shore drilling and in medical devices.
One known route for manufacturing polyether ketone ketone polymers relies on the use of 1,4-bis(4-phenoxybenzoyl)benzene as a starting material.
1,4-bis(4-phenoxybenzoyl)benzene can be prepared by reacting terephthaloyl chloride and diphenyl ether in the presence of a Lewis acid such as aluminum trichloride.
In document U.S. Pat. No. 4,816,556 (example 2), 1,4-bis(4-phenoxybenzoyl)benzene is prepared by dissolving terephthaloyl chloride and diphenyl ether in ortho-dichlorobenzene, cooling to 0-5° C. and adding aluminum chloride with temperature kept below 5° C. The mixture is then warmed to 20° C. Thereafter, cold methanol is added so as to produce a slurry which is filtered, reslurried in methanol and filtered again.
In document U.S. Pat. No. 4,826,947 (example 2), 1,4-bis(4-phenoxybenzoyl)benzene is prepared by providing a mixture of methylene chloride, methylsulfone and aluminum trichloride, cooling to a temperature of between −30 and −35° C., and then adding diphenyl ether and thereafter terephthaloyl chloride. The reaction mixture is then poured into cold methanol so as to make a slurry which is then filtered.
Document WO 95/23821 (example 11) discloses providing aluminum chloride in ortho-dichlorobenzene cooled in an ice bath, and then adding terephthaloyl chloride and diphenyl ether. Thereafter, the reaction mixture is allowed to warm up to room temperature, stirred, and poured into a methanol concentrated HCl solution. A precipitate is formed which is subsequently filtered off.
There is still a need for a method for manufacturing 1,4-bis(4-phenoxybenzoyl)benzene with a high purity and a high yield, which can be implemented at the industrial scale in an economically realistic manner.